caa a22 4500 397494092 CHVBK 20180308164516.0 cr unu---uuuuu 161202e199502 xx s 000 0 eng 10.1093/jb/117.2.324 doi (NATIONALLICENCE)oxford-10.1093/jb/117.2.324 Irradiation with Ultraviolet Light in the Presence of Vanadate Increases Ca2+ Permeability of the Sarcoplasmic Reticulum Membrane via Ca2+-ATPase [Elektronische Daten] [Takashi Hirose, Kazuo Yamasaki, Taibo Yamamoto] The sarcoplasmic reticulum (SR) of rabbit skeletal muscle was irradiated with ultraviolet light (UV) in the presence of vanadate plus 2 mM EGTA, 10 mM MgC1 20% DMSO, and 50 mM PIPES (pH 6.5) at room temperature. In the presence of 100 πM vanadate, the Ca2+ uptake activity of SR rapidly decreased and was almost lost in 20 mm. The activity was inhibited as a function of vanadate concentration with an apparent Ki of about 20 πM. On the other hand, Ca2+-dependent ATP hydrolytic activity as well as phosphoenzyme (EP) formation activity decreased very slowly, and more than 50% of these activities remained 20 mm after initiation of the vanadate-UV treatment. Half inhibition of these activities required about 100 pM vanadate. The loss of the relationship between Ca and ATPase reaction was found to be mainly caused by an increase in the Ca permeability of the SR membrane, which was raised by increasing the vanadate concentration or UV irradiation time in a manner similar to that observed for the Ca2+ uptake. No rise in Ca2+ permeability occurred in liposomes reconstituted from SR lipid when they were irradiated with UV in the presence of 100 pM vanadate. When the vanadate-UV-treated SR was allowed to react with fluoral-P (4-amino-3.penten-2-one), an indicator of aldehyde, and the membrane proteins were separated by HPLC in the presence of SDS, the fluorescent probe was found to be closely associated with the Ca2+ fraction. Furthermore, the amount of fluoral-P incorporation into the Ca increased with UV irradiation time in the presence of vanadate and reached the maximum level at 100 mm. About 7-8 nmol of fluoral-P was bound to 1 mg of Ca2+ at the steady level. These results suggest that when SR is incubated with vanadate under UV irradiation, specific residues in Ca2+ ATPase are oxidized to form aldehyde, which causes an increase in the Ca2+ permeability of the SR membrane. © BY THE JOURNAL OF BIOCHEMISTRY Regular Papers nationallicence Ca -ATPase nationallicence sarcoplasmic reticulum nationallicence ultraviolet irradiation nationallicence uncoupling nationallicence vanadate nationallicence Hirose Takashi Department of Biology, Faculty of Science, Osaka University, Toyonaka, Osaka 560 aut Yamasaki Kazuo Department of Biology, Faculty of Science, Osaka University, Toyonaka, Osaka 560 aut Yamamoto Taibo Department of Biology, Faculty of Science, Osaka University, Toyonaka, Osaka 560 aut The Journal of Biochemistry Oxford University Press 117/2(1995-02), 324-330 0021-924X 117:2<324 1995 117 jbchem https://doi.org/10.1093/jb/117.2.324 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1093/jb/117.2.324 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Hirose Takashi Department of Biology, Faculty of Science, Osaka University, Toyonaka, Osaka 560 aut NATIONALLICENCE 700 1- Yamasaki Kazuo Department of Biology, Faculty of Science, Osaka University, Toyonaka, Osaka 560 aut NATIONALLICENCE 700 1- Yamamoto Taibo Department of Biology, Faculty of Science, Osaka University, Toyonaka, Osaka 560 aut NATIONALLICENCE 773 0- The Journal of Biochemistry Oxford University Press 117/2(1995-02), 324-330 0021-924X 117:2<324 1995 117 jbchem Metadata rights reserved CC BY-NC-4.0 http://creativecommons.org/licenses/by-nc/4.0 nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-oxford